Error is given to below section.

C# Code

Here GlobalApp is my class library...

public List<Student> GetAllStudents()
 
 string sql = "select name,subject,rollNo from students";
 SqlDataReader reader = GlobalApp.GetReader(sql);
 List<Student> students = new List<Student>();
 while (reader.Read())
 
 Student aStudent = new Student();
 aStudent.name = reader["name"];
 aStudent.subject = reader["subject"];
 aStudent.rollNo = reader["rollNo"];
 students.Add(aStudent);
 
 reader.Close();
 GlobalApp.CloseConnection();
 return students;
 
 protected void showAllButton_Click(object sender, EventArgs e)
 
 try
 
 studentsGridView.DataSource = GetAllStudents();
 studentsGridView.DataBind();
 
 catch (Exception exception)
 
 Label1.Text = "" + exception;
 



 

HTML CODE

<asp:GridView ID="studentsGridView" runat="server" Width="226px" CellPadding="4" ForeColor="#333333" GridLines="None">

 <Columns>
 <asp:BoundField DataField="name" HeaderText="Name" />
 <asp:BoundField DataField="subject" HeaderText="Subject" />
 <asp:BoundField DataField="rollNo" HeaderText="Roll No" />
 </Columns>
 </asp:GridView>

Class

public class Student

 public object name get; set; 
 public object subject get; set; 
 public object rollNo get; set; 

System.InvalidOperationException: The data source for GridView with id
'studentsGridView' did not have any properties or attributes from
which to generate columns. Ensure that your data source has content.
at
System.Web.UI.WebControls.GridViewColumnsGenerator.CreateAutoGeneratedFields(Object
dataObject, Control control) at
System.Web.UI.WebControls.AutoFieldsGenerator.GenerateFields(Control
control) at
System.Web.UI.WebControls.GridView.CreateColumns(PagedDataSource
dataSource, Boolean useDataSource) at
System.Web.UI.WebControls.GridView.CreateChildControls(IEnumerable
dataSource, Boolean dataBinding) at
System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable
data) at
System.Web.UI.WebControls.GridView.PerformDataBinding(IEnumerable
data) at
System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable
data) at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments
arguments, DataSourceViewSelectCallback callback) at
System.Web.UI.WebControls.DataBoundControl.PerformSelect() at
System.Web.UI.WebControls.BaseDataBoundControl.DataBind() at
System.Web.UI.WebControls.GridView.DataBind() at
HMS.UI.Start.showAllButton_Click(Object sender, EventArgs e) in
e:ProjectsHMSHMSDefault.aspx.cs:line 80